<!DOCTYPE html>
<html lang="en">
<head>
<!--
style:方式
-->
    <meta charset="UTF-8">
    <title>09-CSS选择器</title>
    <style type="text/css">
      h1 {color: red}
      .test{color: blue}
      #a{color: green}
      div span{color: orange}
    </style>
</head>
<body>
<h1>我是h1</h1>
<h2>我是h2</h2>

<p class="test">源码时代</p>
<p class="test">源码时代</p>
<p class="no_test">源码时代</p>

<p id="a">id选择器</p>
<p>id选择器</p>

<div>
  <span>span标签</span>
  <span>span标签</span>
  <p>p标签</p>
  <div>
    <span>span标签<p>P2标签</p></span>
  </div>
</div>

<h1>h1标签</h1>
<h2>h2标签</h2>
<h3>h3标签</h3>
</body>
</html>